MULE 4 : Batch Process : How does the batch process component process records in a collection?

Question

Scenario : I have 2 source database tables [ Student_INFO, Teachers_INFO] from where I will pull data using a Scheduler in every 1 hour.

STUDENT_INFO contains :

1. Student name
2. Student roll number
3. Subjects taken by the student for example MATHS, ENG, SCIENCE, ARTS

TEACHERS_INFO contains :

1. Teacher Name
2. Subject taught by the teacher for example MATHS

My expected output is to group against each teacher the students taught by him. To do this, I want to

1. collect the data from the two sources
2. Create a map having teachers name as key and then iterate through students subjects and add them to the teacher map

Now I have the code ready using a for each loop n MULE 4

But I am unable to understand how to do the same in batch processing. Can someone please help me visualize the problem from MULE 4 batch processing scope?

Thanks for your help.